About 1900 it was prescribed for the first time that taxi fares have to be automatically determined and indicated by a taximeter. Appearance and function of the instruments have meanwhile changed substantially. The pictures show historical instruments from 1900 and 1960 and two modern instruments. Modern designs are microprocessor-controlled computers which offer a great variety of possibilities of automatically setting the tariffs. The automatic preselection of a tariff by the internal watch is of particular importance. It allows day and night tariffs, weekend tariffs etc. to be set, the change from summer to winter time and vice versa also taking place automatically. The greatest part of the test work carried out by the PTB within the scope of type examinations concerns the testing of such optional models.